This is a working draft for Leslie's review. The dependency edges below are a first pass — the diagram and the prerequisite table are the parts to check hardest, since they drive hold-vs-advance decisions.
The course map shows the eight units as a spine — cells first, Plants, Ecosystems & People last. But the real prerequisite structure isn't a straight line: it's a directed graph. Botany is more strictly cumulative than most subjects — organ anatomy needs cells and tissues, photosynthesis needs leaf anatomy, growth needs both photosynthesis and transport. A weak concept early doesn't just lower one grade, it cascades into everything downstream that needs it. This page is the map a guide uses to find the concept that's actually blocking a stuck student.
An arrow means “must be mastered first.” Units 05, 06, and 08 each pull from two upstream units — those are the cascade points where one soft prerequisite quietly breaks several later units.
Prerequisite gating
A unit unlocks when its prerequisites are mastered — demonstrated, not merely seen. "Covered in class" is not the gate; a cleared rubric is. The difference matters most at the cascade points, where a soft prerequisite quietly breaks two or three later units.
| Unit | Must have mastered first |
|---|---|
| 01 Plant Cells & Tissues | — (entry point) |
| 02 Roots, Stems & Leaves | 01 (organs are built from cells & tissues) |
| 03 Photosynthesis & Plant Energy | 02 (photosynthesis is a leaf-tissue process) |
| 04 Water & Nutrient Transport | 02 (xylem & phloem are stem and root tissues) |
| 05 Plant Growth & Hormones | 03 (growth is powered by photosynthesis) + 04 (growth needs water & mineral nutrients) |
| 06 Flowers, Seeds & Fruit | 03 (flowering & fruiting are energetically costly) + 05 (hormones trigger the switch to flowering) |
| 07 Plant Diversity & Classification | 05 (growth form & life history are classifying traits) |
| 08 Plants, Ecosystems & People | 06 (reproduction drives crops & seed) + 07 (diversity structures ecosystems) |
Gap-cascade diagnosis
When a student stalls late, the visible symptom is rarely the real problem — the broken concept is usually upstream. Trace the arrows backward. Common cascades:
| Late symptom | Upstream concept to check first |
|---|---|
| Classification keys don't resolve (Unit 07) | Growth form & life history from Unit 05 — those are the traits a key sorts on. |
| Flowering & fruiting don't cohere (Unit 06) | Hormonal control of growth from Unit 05 — flowering is a growth transition, not a separate system. |
| Ecosystem roles won't fit together (Unit 08) | Plant diversity from Unit 07 — you can't place a plant in a community you can't classify. |
| Growth & hormone reasoning goes wrong (Unit 05) | Where the energy comes from — Unit 03, Photosynthesis & Plant Energy. |
Using the graph to plan a re-attempt
The graph turns a "not yet" into a targeted re-attempt instead of a whole-unit re-teach. When a student fails a downstream demonstration:
- Trace backward to the upstream node the symptom points to.
- Re-attempt the upstream concept first — close the gap at its source, not where it surfaced.
- Then re-run the downstream demonstration. Often it passes without any re-teaching of the downstream unit at all, because the cascade is resolved.
This is also where the integration guide matters: some botany concepts depend on an idea from another spoke — ratio and proportional reasoning for surface-area-to-volume, statistics for comparing growth data, history and genetics for Mendel's pea garden. When the upstream botany node looks solid but the student still stalls, check the cross-disciplinary dependency before re-teaching the botany.